Δαφνη Ευτυχια Αρθουρος

If you're flying with a groundspeed of 2100 MPH and have a tail wind of 2100 MPH, unless you're extremely bouyant, you're falling like a rock :-P

So then by delta v, are you talking about one body's velocity relative to another, or to one body's change in velocity (which can be measured locally by an accellerometer with no outside reference--changing from 1mph to 2mph registeres the same total delta v as the change from 300 to 301)? Mach is a relative measure: your speed relative to the air around you. I instantly jumped into all the fizzix problems that they threw at me all through college where delta v refers specifically to the change in velocity that a single body undergoes. Divide delta v by time and you get the impulse, which is essentially how much of a jolt you get. This impulse is what, say, kills you if you jump off a tall building and don't die of heart failure before you have your brief and sudden stop.

I'm still thinking that there are situations where your speed, and your speed-induced interaction with the surroundings, will be what cause your demise.

Let's say (since I always like the physics of killing people by tossing them out of planes--it's all because of my first fizzix teacher, Mr. Morris) that instead of throwing you out of a jet moving with sufficient airspeed to turn the nosecone cherry-red and leaving you to your eventual demise, we were to strap you to the nosecone once we've reached this hot speed. If the engines keep on, you'll have no delta v (by the definition I'm used to) whatsoever, but you'll end up some unpleasant combination of crispy and mushy by the end of a few minutes.